1. Field of the Invention
The present invention relates generally to a paper advance mechanism and a printer using the same.
2. Description of the Prior Art
FIG. 4 shows a cross-sectional view of a conventional printer. As shown in FIG. 4, a separate paper roller 63 moves a sheet from a drawer to a gap 69 defined between a guide 65 and a paper feed roller 68 which is rotated to advance the sheet through a channel 70 defined between the guide 65 and a guide 66 to two driving rollers 64. The two driving rollers 64 move the sheet in a direction from the channel 70 to a gap 71 defined between a printer head 61 and a platen 62 so that the printer head 61 prints image on the sheet on the platen 62. After the sheet is printed, the driving rollers 64 move the sheet in an opposite direction from the gap 71 along the channel 70 and a channel 72 defined between the guide 66 and a guide 67.
FIG. 5 shows a cross-sectional view of another conventional printer. As shown in FIG. 5, this printer has a path change plate 88 including an end resting on a guide 85 and an opposite end pivotably mounted on an end of a guide 87. In this printer, a sheet advanced by an individual paper roller 83 is initially moved along an inclined surface of the guide 85, and then push away the path change plate 88 to reach two driving rollers 84 by way of a channel 89 defined between the guide 85 and a guide 86. The driving rollers 84 move the sheet in a direction from the channel 89 to a gap 90 defined between a printer head 81 and a platen 82 such that the printer head 81 prints image on the sheet on the platen 82. After the sheet is printed, the driver rollers 84 move it in an opposite direction from the gap 90 along the channel 89 and a channel 91 defined between the guide 86 and the path change plate 88 and a guide 87.
The printer shown in FIG. 4 uses the paper feed roller 68 as well as the guides 65-67 so as to change paper path, and the printer shown in FIG. 5 uses the path change plate 88 as well as the guides 85-86 so as to change paper path. Such mechanisms for changing paper path entail disadvantages in complicated structure and tough assembly.